The Linux Soundfile Editor Roundup

Whether you're making nifty sounds for desktop events or recording a whole album, you'll need one of these featureful sound apps.

MiXViews 1.30

The 1.0 release of Doug Scott's MiXViews occurred in 1995, making it
the longest-living Linux soundfile editor profiled here. MiXViews was
and is a one-man effort to provide UNIX and Linux with a high-quality audio
editor. The project continues to be a solo development effort, and it
still provides a high-quality editor.

MiXViews provides a strong suite of the basic soundfile editing
functions and adds some features found in no other Linux soundfile
editor. Phase vocoding and linear predictive coding (LPC) are digital
signal analysis/resynthesis tools more commonly associated with software
sound synthesis programs such as Csound or Common Lisp Music. These
tools analyze a sound for its frequency and amplitude values and store
those values in special analysis file formats. An analysis file can
be read by a program such as Csound that gives the user
independent control over the frequency and amplitude components of the
analysis data before its resynthesis to a soundfile. MiXViews provides
a complete suite of its own LPC and phase vocoder utilities; it also
can read and edit analysis files created by the Csound phase
vocoder.

Figure 3 displays some of MiXViews' graphic tools
for editing phase vocoder and LPC analysis data. Although the theory
and mathematics behind these tools can be intimidating, the MiXViews
interface invites experimentation, making the tools themselves easier
and more interesting to use.

If you want to try MiXViews, I suggest using the prebuilt
binary. Compiling MiXViews is somewhat tricky, and it requires an uncommon
graphics toolkit (InterViews), so simply download the static binary and
start using it.

Figure 3. MiXViews

DAP 2.1.4

DAP (the Digital Audio Processor) is programmer Richard Kent's
contribution to multiplatform soundfile editors. Like MiXViews,
DAP's GUI is based on a not-so-new GUI toolkit, the XForms library.
Also like MiXViews, DAP's workable soundfile size is limited by your
system RAM. In addition, DAP includes
some exceptionally well-implemented loop editing tools
for AIFF soundfiles. DAP also includes a good selection of DSP modules
(extended from Kai Lassfolk's SPKit code) and a handy mono-to-stereo
and mono/stereo-to-quad converter.

Some of DAP's editing tools deserve special mention, particularly
those found in the Resample and Edit/Mix dialogs. The Resample menu
provides pitch and sample rate change with or without time stretching,
while the Edit/Mix dialogs (Mix and Mix Range) provide a neat graphic
control over the balance of the mixed file amplitudes. The influence
of the AIFF file format and its loop support is found throughout the
program. For example, when an effect is applied to a file the DSP dialog
panel provides a control for the iterations of the sustain and release
loops (Figure 4). Although DAP's design is biased toward the AIFF format,
it also imports and exports files in RAW and WAV formats.

Alas, DAP is no longer consistently maintained. Its XForms GUI is showing
its age, and its file size limitation is a serious drawback. The author
is honest about DAP's limitations, but if you're working with AIFF
files with embedded loop points, DAP is still a useful tool.

Figure 4. DAP

The next group of editors belong to the new wave of Linux audio
development. Their natural environment includes the modern graphic
interface toolkits and the newer Linux sound system components, such as
ALSA, JACK and LADSPA. They also are conceptually more homogenous than
their predecessors, offering resemblance to the popular editors
familiar to Windows and Mac users.

Audacity 1.1.3

Audacity is a fitting first representative of this new wave of
Linux soundfile editors. It is written in C/C++, uses the wxWindows
cross-platform GUI toolkit and supports native and LADSPA signal
processing plugins. Recent versions also are JACK-aware, giving Audacity
the ability to route its I/O to or from other active JACK-aware programs.

Audacity's graphic editing tools are a pleasure to use. Figure 6 shows off the
envelope tool's effect on the amplitude contour of one of the soundfiles
seen in Figure 5. At the individual sample level, Audacity's drawing
tool makes it easy to remove or repair amplitude spikes and other
discontinuities.

Like Snd, Audacity features an interface to a Lisp-based programming
language, Roger Dannenberg's Nyquist. Nyquist is a language designed
for sound synthesis and signal processing, and Audacity's Effects menu
provides a Nyquist Prompt that works essentially like Snd's Listener. You
enter a Nyquist expression in the prompt dialog, click on the OK button
and if the expression is valid, Audacity performs the intended process
on the active soundfile.

There's far more to Audacity than I can possibly describe
here. Fortunately, the program is easy to learn and use, so check
it out for yourself.

Very nice article, this kind of topic should be appearing more on linux journal. Linux audio scene is a little behind the win but it is very good !!
Congrats for the article and nice presentation of each program.
I really liked the screenshots !!